Influência de diversos tratamentos térmicos na microestrutura e dureza do aço 1045.

Abstract

SAE 1045 steel is a carbon steel with medium carbon content in its chemical composition, which makes it a common steel with medium mechanical properties and low hardenability, being used in structural and machinery components, shafts, common gears, crankshafts and forged parts. This work proposes to analyze the microstructural variations of SAE 1045 steel according to the heat treatments used: annealing, normalization, water quenching, brine quenching and quenching in water followed by tempering. For this, the hardness obtained in each of the samples submitted to heat treatments will first be analyzed and compared with each other, as well as with the initial sample. Then, the optical microstructures obtained in each of the samples submitted to heat treatments were analyzed and compared with each other, as well as with the initial sample. It was concluded that the hardness and optical microscopy results were in agreement with the researched literature, in which the heat quenching treatments resulted in a higher hardness according to the produced martensitic needles, with the water quenching being the largest, followed by brine and tempered water due to the stress reduction characteristic of tempering. In the procedures of full annealing and normalization, it was possible to observe a high growth of pro-eutectoid ferrite, characteristic of hypoeutectoid steels such as SAE 1045, mainly in the annealing heat treatment due to its slow cooling in the off furnace.